How to Refinish a Stained, Water-Damaged Window Sash

Oil-based exterior stain is best for window sashes.

Moisture problems are common on wooden-framed windows. They have direct water exposure from the outside and sometimes condensation forms on the inside. At some point the original sash — the wood that holds the window in place -— may become discolored or water damaged. A common misconception is that it's best to finish window sashes with a topcoat of shellac, polyurethane or varnish, but that's actually where the problem originates. These types of coatings will not hold up, resulting in damaged wood. To refinish a stained sash, old coatings and loose wood fibers must first be removed before an application of oil-based exterior stain is applied.

1

Scrub the window sash with a stiff, wire brush. Scrub with authority using strokes parallel with the grain only. Remove as much of the old finish and loose fibers of wood as possible.

2

Sand the sash by hand with a folded piece of 80-grit sandpaper. Finish removing all of the old finish with the sandpaper. Scrub and sand with authority, using strokes parallel to the grain only.

3

Resand the sash again, using 100-grit sandpaper. Sand until the sash has a uniform color. It's OK if there are light blotches or darker areas in the wood as they will blend in later.

4

Fill all of the holes, gouges, splits or cracks, using a color-matched exterior caulk. Smooth the surface of the caulk, using a wet fingertip. Allow the caulk to dry for 24 hours.

5

Dip a paintbrush into an open can of exterior oil-based stain. Brush the stain onto the sash. Liberally coat it with the stain. Allow the wet stain to remain on the sash for 15 minutes, then wipe it off with a soft cloth. Allow the stain to dry for 72 hours.

6

Brush another coat of stain onto the sash. Allow it to dry for 15 minutes and wipe it off.

Things You Will Need

Wire brush

Sandpaper, 80-grit

Sandpaper, 100-grit

Exterior caulk

Paintbrush

Exterior oil-based stain

Cloth

Tips

Do not add any type of topcoat to the stain. This type of stain penetrates into the pores of the wood and hardens to protect from the inside out.

Choose a color that matches existing woodwork in your home.

Apply a coat of woodworker's paste wax to the sash for a more glossy look, if desired.

Warnings

If you get stain on the metal parts of the window, wipe them clean with a cloth dampened with lacquer thinner.

Always wear breathing and eye protection when working with wood or wood-finishing products.

About the Author

Specializing in hardwood furniture, trim carpentry, cabinets, home improvement and architectural millwork, Wade Shaddy has worked in homebuilding since 1972. Shaddy has also worked as a newspaper reporter and writer, and as a contributing writer for Bicycling Magazine. Shaddy began publishing in various magazines in 1992, and published a novel, “Dark Canyon,” in 2008.